In his opening remarks at the impeachment hearing Tuesday, Lt. Col. Alexander Vindman casually mentioned the other part of Washington’s intense focus.

“The uniform I wear today is of the U.S. Army,” said Vindman, the top Ukraine expert on the National Security Council who raised alarms over whether President Trump asked Ukraine for political help in exchange for military aid.

But Vindman and his Army service uniform, adorned with a Purple Heart, Ranger Tab and Combat Infantry Badge, have become proxy symbols, either bolstering claims of Democrats or used as evidence by Republicans that Vindman is using his service as a shield from criticism.

And while active-duty service members routinely wear their full uniforms to testify on Capitol Hill, security experts say the scrutiny of Vindman’s uniform has become another data point in the politicization of the space between civil society and the military.

The Army’s bible for appearance standards, AR 670-1, says all personnel “will wear an Army uniform when on duty, unless granted an exception by the commander to wear civilian clothes.”

“Most reactions to it imply a choice where there is not one. Commentators are projecting their own feelings without understanding military regulations, a pretty frequent occurrence in civil-military relations,” said Loren DeJonge Schulman, a former Obama defense official who advised national security adviser Susan E. Rice.

“People are seeing what they want to see regarding the clothes Uncle Sam laid out for Vindman today,” said Schulman, a security and civil-military relations expert at the Center for a New American Security.

President Trump mentioned Vindman in a Cabinet meeting during the hearing in an apparent swipe at his dress selection. “I never saw the man, I understand now he wears his uniform when he goes in,” Trump said.

Army officials referred duty uniform questions to the NSC. Officials there declined to say what their role was, if any, in prescribing what Vindman should wear. Vindman also wore his uniform during a closed door deposition in October.

Military officials assigned to the NSC typically wear formal civilian clothes on a council blended with many other agency representatives, said Steve Miska, a retired Army colonel who served on a rotation at the NSC in 2011.

Wearing a uniform in that environment “gives the appearance that because I’m in uniform, I’m running the agenda,” when in fact, both military experience and security expertise are the reasons officers receive those positions.

However, wearing a uniform during testimony is “probably appropriate” for Vindman, he said. “That’s your dress attire expected for that level of formality.”

H.R. McMaster, who served as Trump’s national security adviser while a three-star general, often wore a suit and tie in public appearances.

That role differs from other senior military officials, who wear their uniform while testifying for lawmakers or meeting with the president in their capacity.

Perhaps most famously, Marine Lt. Col. Oliver North wore his service medal complete with ribbons in 1987 when he testified about his involvement in the Iran-Contra affair.

During the testimony, Rep. Chris Stewart (R-Utah) led an attack on Vindman’s choice of uniform, noting that he wears a suit, not a uniform, while at the White House. The uniform is a “great reminder of your service,” Stewart said, providing backhanded compliments while pressing Vindman on his request to Rep. Devin Nunes (R-Calif.) to call him by his rank, rather than “Mr. Vindman.”

“Do you always insist on civilians calling you by your rank?” Stewart said. “The attacks I’ve had in the press, [on] Twitter have kind of … marginalized me as a military officer,” Vindman replied.

Veterans, officials and reporters have also weighed in, complicating the understanding.

“Vindman absolutely had a choice, and he ran with it,” one former officer told the Washington Examiner in a news report that suggested it was part of a deliberate “influence op,” as another anonymous officer who worked in psychological operations put it.

Maggie Haberman, a New York Times political reporter, said during the opening remarks that Nunes focused on attacking the media because it would be easier than to “challenge a witness in dress uniform.”

Ben Siegel, an ABC political reporter, alerted his followers Tuesday morning that Vindman would appear in uniform, implying an unusual decision that fed intrigue.

Haberman’s takeaway illustrates a broad idea of deference to the military as an institution, one that Trump has relied on and Republicans have traditionally tried to corner as the party of respect to the uniform, said Jason Dempsey, a former Army officer.

Now, some Democrats, with their explicit rounds of ‘thank you for your service’-esque bromides during the hearing, have tried to do the same to bolster public support of impeachment, Dempsey said.

“The outsize symbolism attached to uniform is like a totem that everyone wants to co-opt to say, ‘I can use this to my advantage,’ ” said Dempsey, who writes on civil-military affairs as an adjunct senior fellow at CNAS.

The fierce debate has focused on the credibility of Vindman himself. He was attacked by Trump as a “Never Trumper” witness, joining GOP lawmakers such as Sen. Ron Johnson (R-Wis.) in describing Vindman as a threat from the inside. Conservative commentators such as Laura Ingraham have also joined the fray.

Attacks have concerned officials to such a degree that the Army is “providing supportive assistance to help Lt. Col. Vindman with the public attention,” an Army spokeswoman said, and the Wall Street Journal reported the Army was taking security precautions for Vindman and his family.

“Its fascinating how quickly they will abandon anyone in uniform if they don’t fill preconceived notions of who you should support,” Dempsey said, referring to Republicans and broad public perception that the service is filled with conservatives.

“There’s almost this knee-jerk, immediate reaction to undercut the validity of his service.”

Elise Viebeck contributed to this report.

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